campbjell



April 5,1927.` 1,623,575

c. E. CAMPBELL x-RAY AJPPARATUS mi. W

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vApril `5, 1927'. 1,623,575 C. CAMPBELL X-RAY APPARATUS Filed Julyl4, 1920 10 Sheets-Sheet I5 April 5,1927. Y 1,623,575 A C. E. CAMPBELL X-RAY APPARATUS Filed Ju1y14, 1920 C. E. CAMPBELL x-RAY APPARATUS Filed J1y14. 1920 A 1o sheets-sheet s April s, 1921. 1,623,515

April 5,- 1927. l,623575 v C. E. CAMPBELE X-RAY APPARATUS Filed Julyl4, 1920 10 Sheets-Sheet 6 'Y mm a HMM April 5, 1927.

c. E. CAMPBELL x-RAY APPARATUS Fiied Ju1y14. 1920 l0 Sheetsheet c. E. CAMPBELL x-RAY APPARATUS Filed Ju1y14. 19,20

April 5 1927.

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vApril 5, 1927.

c. E. cAMPBELL X-HAY APPARATUS Filed Julm. 1920 l0 Sheets-Sheet 9 1,623,575 Afprnil 5 1927. c. E. CAMPBELL X-RAY APPARATUS Filed Juilylfz, 1920 1o sheets-sheet 1o Patented Apr.Y s, 1927.

i UNITED STATES PATENT OFFICE.;

ciiAaLES E. CAMrBELL, or LfYNN, MASSACHUSETTS, ASSIGNo-n To'CAiuPBEi.L ELEC- Tmc coMPANr, or LYNN, MASSACHUSETTS, AConroNATioN or MASSACHUSETTS.

x-nAY APPARATUS.v

Application led July 14,

The present invention relates to X-ray' apparatus, and more particularly to Xi-ray tables employed for making X- ray examinations and radiographs..

The object ofthe presentv invention is to provide a new and improved form of X-ray table which facilitates the examination and radiographing of any desired portion ofthe human'anato y. With" this object in viewthe several characteristics of the invention consist in certain novel features of construction andcombinations and arrangements of parts hereinafter described and claimed, vthe advantages of which will be obviousto those skilled in the nrt from the following description.

In the accompanying drawings illustrati-N ing thefpreferred form ofthe invention, Figure 1 represents a side elevatlon ofvan X-ray .table embodying the several features of the invention; Figure 2 is an end view of the X-ray table with the bed portion located 1n l La substantially vertical position to .show the in Figure 9; 'Figure 11 is a section upon the mechanism beneath the bed; Figure -3 is a detail illustrating a plan view of the slipporting base separated from the table; Figure 4 is a detail showin a section upon the line 4 4' of Figure 3;- igure 5 is adetail `showing anelevatioi partlyin sectionfof the motor driving mechanism l for tilting the.v

table; Figure 6 is a plan view #of the-motor 'driving mechanism shown in Figure frvith the cap removed from the enclosingcasing; Figure 7.is a detail illustrating a section of the motor switch box showing the switches for automatically limiting the tilting movement of the table in opposite directions; Figure 8 is a detail illustrating an' elevation partly in section ofthe tube carriage; Fig- 'ure 9 is a detail illustrating the mechanism for controlling the movement of the shutf ters; Figure 10 is another view 'of thecon'- trolling mechanism for the shutters shown showing aplan view of the dial-for indicating theproper shutter opening at any given he'ght of the plate holding device above the I ta le; Figure 13 is a detail showing a Crosssection of the handles for controlling the,

movements of the two shutters; Figure 14`is a detail illustrating the connection by vvhich the table top is hinged to the frame; Figure 15is a plan'view of the mechanism fer holding the uorescent screen in'place; Figure 16 26;-26 o f Figure 24; Figure 27 is a cross- 1920. Serii ita-saches.

Figure 15; Figure 17 is a detail ofthe etachable connection for fastening the screen` frame the holder; Figure 18 is a detail illustrating a sectionalelevation ofv the yie1d ing connection between the counter-weight and the tube carriage; Figure 19 is a sectional plan of the tube v carriage counter- 'weight and connecting mechanism; Figure a side elevation partly in section of the me'chanism .shown inxFigure 23; Figure 25is a cross-section upon the line 25-25 ofSFigure 'iis a side elevation ofthe mechanism shown 'n J 24; Figure 26 is a cross-section upon the line section upon the line 27-#27 of Figure .24; Figure 28 is a detail illustrating a front elevation of the foot rest; Figure 29 is a view of the restshown in' Figure 28 taken at right angles thereto; Figure 30 is a sectionJ of the rest and mechanism for locking it' upon .the table, taken upon the linev 30-3() of Figure 29; Figure 31 is a detail illustrating a view of the'adjustable resistance employed for controlling the flow of current through -t-he filament.

tio'n comprises a table indicated generally at 0i i The illustrated-embodin'ient of the inveni 10, which is supported for tilting movement between ltwo side standards-12 and 13.' Each of the side standards is provided withv two adjustable feet 11 by which the table, may` be leveled with respect to the floor.'v The.

table, as will be observed from aninspection of Figure2, is provided with oppositely extending pivot shafts A14*v and 15 which are' received in bearings formed in-the `tops of the standards. .The table-is preferably tilted as a whole through a gear segment 17 secured vto .the side of the table insideof the standard 12l and meshing with a'driving pinion 19.v The driving pinion 1s normally'actuated to t'iltthe table through an electric motor,

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but the connections are so designedthat the motor may bel disconnected and the'itable tilted by hand, if so desired. Y To this end,

an electric driving motor 21 is mounted upon the main base plate 23, and is connected with the driving pinion 19 through a double reduction worm gearing consisting ofJ a worm 25, mounted upon the motor shaft 27, a driven gear 29, a worm 31 mounted upon the gear shaft, and an intermeshlng ear. 33 secured to the shaft carrying the. rlvmg pinion 19. It will be observed that this gearing as a whole is enclosed in a caslng 35, forming an integral part of the base plate 23. In order to conveniently disconnect' the motor drive from the table 10, and to permit the movement of the table by hand, the driving pinion 19 is splined upon the shaft37 and is normally retained in the position shown in Figures 5 and 6 by a spring 39, which bears against one side of an annular lange 41 formed as a part of the hub 43. The opposite side of the flan e is engaged by the two arms of a shifting ork 45, which is ulcrumed upon a shaft 46 extending outside the gear easing. This shaft outside'of the casing is provided with an operatin4 arm 47, which is connected with a foot trea le 49 through a short connecting rod 51. It will thus be observed that although the movement of the table is normally controlled by the electric motor 21, a depression of the foot treadle 49 will disconnect the driving pinion 19 from the gear segment 17, and permit the table to be moved manually. The operation of the electric motor 21- may be conveniently controlled through a suitable form of foot switch, as indicated at 53 in Figure 2, connected with the motor through a ilexible cable indicated at 55. It is desirable to provide means for automatically limiting theA movement of the table in opposite directions in the event that the motor circuit is inadvertently left closed too long. To this' end a switch box57 is mounted above the gear easing and contains two sets of members which automatically open the motorcircuit when the table has moved a predetermined distance in either direction. As will be observed from an inspection of Figure 7 of the drawings, the upper portion of the switch box is provided with terminals ,61, 63, and 67, which are adapted to he connected into the motor circuit. The terminals 6l and 65 are provid d with spring contact members 69 and 71, ,hich are normally adapted to engage stationary contacts formed upon the inner ends of the terminals 63 and 67 to close the circuit. This engagement of the two sets of contacts is secured through arms 73 and 75, which are supported upon the inner ends of shafts 77 and 79, normally constrained to keep both arms 'in the position shown at the right in Figure 7 by coil springs 81. The v,outer end of each of the shafts 77 and 79 adjacent the ear segment 17 'is provided with an outstan ing arm 83 supported respectively in the path of movement of studs 85 and 87, projecting from the side of the gear segment. It will be obvious to those skilled in the art from an inspection of the drawings that with this construction, when the table is tilted in opposite directions to an extreme position, one of the studs 85 or 87 will engage. with the corresponding arm 83 to permit the contact members .to separate Y and automatically break the motor circuit. In this connection it may be stated that the motor 21 is of the familiar repulsion type which is designed to rotate in opposite directions, depending upon the circuit arrangement. In order to snit.- ably control the rotation of the motor, the. foot switch 53 is formed in two parts so that an actuation of each part will control the rotation of the motor in one direction.

In order that the operator may convenientlybe informed as to the angle of inclination of the table, an indicating dial 91 is formed upon the standard 12 and cooperates with an indicator hand 93 secured to the shaft 14 outside ofthe bearing. It will be observed from an inspection of Figure 1 that when the table is in a horizontal position, `the indicator hand is in approximately the position indicated with respect to the dial. 'In this position the indicator hand has a sutiicient range of movement with respect to the dial to permit the right hand end of the table to be 'moved downwardly until the table assumes approximately a vertical position or to permit the left hand end of the table to be dropped a substantial amount to incline the table in the opposite direction. In other words, the table construction is such that it may 'be rocked in opposite directions, thus permitting the patient to be moved into the Trendelenberg position, so called, in which the head is lower'than the remaining portion of the body.

The table is provided with two longitudinal tubular supports 95 and 97 which support upon their opposite ends castings 99 and 101, which in turn lsupport a Hat bed 103 of wood or other suitable material, which may be hinged to the supports as indicated in Figure 14, to permit it to lbe swung out of the way if so desired. It is essential, to provide a rest for -the head or feet, or both, of a patient upon the table, and to this end a new form of rest is employed in'connection with the table, which may be readily adjusted at various angles, or may be entirely removed from the table, if so desired. The head and foot rests are indicated respectively in Figure 1 at 105 and 107. As the two/rests have the same construction and mode of operation, only a single reet will be described. Each of the rests ,is provided with a lat support 109, which is pivoted at its lower or inner edge upon oppositely1 extending studs 111, which are received in side plates 113.l The support :dium of lclamp edly en age wlth the outer ends of the studs 109' is clamped inany angular position with relation to the side jatesthrough Athe memem ls 115 which thread- 111. T e upper portion of the support 109 isl connected at opposite sides to the front of cach side'plate 'by a diagonal strut117, which j necting b0lt125 is provided at its-inner end with an enlarged head. 127, which slides -within a T-shaped slot 129 formed in the edge of the support. The outer end of vthe bolt ,threadedly engages with a wing nut 131,

which may be tightened to clamp'thesupport 109, thev slide 121 and the strut 117, .rlgldly together." It willA be observed that withthis construction,- not only maythe support 109 be adjusted to any inclination relative to the bed of thetable, but in addition the support ,may be adjusted into a position in which 1t lies Hat lalong the bed, thusv substantially'v moving it out-ofthe way. In addition tothe 4adjustment of the angle of the support, the

' restas a whole may be adjusted lengthwise f of the table, or entirely removed,yif so desired. In :order to make'this latter adjusti ment possible, thekside plates 113 are providedwith inturned flanges 133, each ange having a: stud 135 projecting upwardly therefrom intoone lof a seriesv ofrecesses formed in the parallel channel irons 137 supporting `the"'be'd'103. In addition, the side plate is provided with a boss 139 whichA receives a pin 141 having its inner end `143V project-l mg over the top df the bed, as shown in Figure 30, to retain the side plates inthe'relative positions shown in Figuresy 28 and 30.

The pin 141 is vnormally retained inyan operativeposition by a sprin 145, and is providi ed upon its outer end w1th a handle 147 by the position shown. #This :mechanism no1"- mally serves to retain the rest locked in lon'- gitudinal. position with respect to the bed,

but upon withdrawalof the pins l141, Vthe front end of the rest may be dropped'suililcientlyto disengag'e thel pins j 135 from` the corresponding recesses, and-the vrest either moved to a new position longitudinally of the table, ,or completely removedl from-the table altogether. In order topermit the desired rangeof the adjustment ofthe rests,

itis obvious thatthe under side` of the bed must be provided with a series of pin receivingv recesses located theI proper distance apart.

f In accordance with the above described coni' p v struction it will be evident that the rest may thrown upon the screen. Connected with 'be moved substantially through an arc of' 180, permitting it to be adjusted into any one of several positions Vin which it may be, either parallel with the table top or vin- A clined with relation thereto.

zontal or'an inclined' position, the patient will rest thereon, but for certain purposes it may be desirable for the patient to stand erect during the examination or taking of radiographs. To this end the table may be tilted into afsubstantially vertical position exposing a` turn table 151 having a foot rest 153v of soft" rubber, or other material. The turn table is swivelled upon thebase 23 at 155, and is supported for `rotary movement by anti-friction bearings 157, which travel in When the table is located in either a hori` an annular ball race 159 formed in the base,

the individual bearingv members being scparated'by` suitable spacing members 161. Ille-freely movable turn table .is a great convenience, as -it permits the patient to' j be turned completely around with a slight tlort, permititng the X-rays' to be directed oward the, body at any desired angle.

-The present apparatus is self-contained in the sense that the transformer forproducing the requisite voltage used in the source of X-ray is embodied in the table. in such` a manner that the high tension leads con- I necting the transformer with the source f X-ray are completely removed from .the operator. With this construction the only leads connecting the table with the source v of supply are low tension leads carrying current at commercial voltage, which do not form 'a source ofdanger to the person operating the table. The advantages of'such a nconstruction will. be obvious to those 5*' skilled in the art. To this end the present invention comprises a transformer orsimi larjmechanism 'supported uponthe under "sldeof the tablein a lstationa'rv'position7 and 1 vconnected withthe'sourc'e oflX-ray through suitably disposed 4iexible `leads;v- Thev .X-ray vtube, is supported upon` a? carriage beneath- A the table, and is adjustable'-hothlongitudij which the end 143. may be Withdrawny from vlll! nally' and transversely'ofthe'tableffthrough to the tube, the `carriage v alsol carries a yaligned with the tube, and is adjustable in l orderv that the best positin 'with relation` to the organ to beexamined may be. secured.

The frame* carrying the screen in addition contains a receptacle for radiographic plates directlyI beneath the screen, so that the image ofthe object to be radiographed may be first cast upon the screen, and then the radiograph taken with the-assurancethat it will -be located identical with the image the carriage is a mechanism for operating the shutters, so designed that the proper shutter opening may be obtained for any desired size nt' picture in different given lpositions of thlscreen and plates abovethe surface of the ta e.

In the illustrated embodiment of the invention, a travelling carria e indicated at 165 is supported for longitu inal movement upon the tubular members95 and 97. The carriage, as will be evident from an inspection of Figures 1 and 2, is freely movable along the members through the medium of cooperating antilfrietion rolls 167 and 169.l which are journaled at the four corners of the carriage and engage opposite sides of each standard, as indicated. In addition to its movement longitudinally ofthe table, the carriage has provision for movement transversely of the table, and to this end two transversely arranged tubular members 171 and 173 are provided, upon which moves the tube carrying frame 175. This frame is supported upon the tubular members 171 -and 173 through the medium of anti-friction rolls 177 and 179, engaging with opposite sides respectively of the tubular members, as indicated clearly in Figure 8. The frame 175 carries upon its under side an X-ray tube 181. This tube is connected to the carriage through a. plurality of depending posts 183 and cooperating clamps 185 and 187, which are supported upon the posts and insulated,from the carriage by sleeves'189.

' As shown in Figure 2, lead'plates 190 are held under sleeves 189. The tube is held ,rigidly between the clamping members by knurled nuts 191 threaded upon the lower end of the standards. The tubeshield, as shown in the drawings, is formed of a material opaque to X-ray emanatlons, such as lead glass, or the tube-may be enclosed in any desired ,zform of container' which is opaque to these emanations. As indicated, the tube is provided with an upwardly d1- rected opening 193-through which the X- rays pass, and a hollow sleeve 195 extends downwardly from the carriage Aand provides an opening to confine the X-rays to the proper path. A screen andplate holder is supported upon the carriage above the table, and to this end a bracket 200 is secured to the frame 17 5 and slidingly receives parallel supporting membersk 202 which carry a screen and plate frame Indicated at 204 upon their upper ends. members are rigidly connected at their upper and lower ends by heads 206 and 207, and are provided with rack teeth 208 which mesh with operating pinions -209 and 21.0 journaled within the head 200. The pmion 209 is mounted upon a shaft 212 provided upon its outer end with a knurled handle 214- by which the pinion 209 and the intermeshing n pinion 210 may be rotated in opposite direc- Aagainst rotation relative to the supporting casing by a stud 220 received in a longitudinal slot on the pin. The hub 215 is provided with a series of longitudinal slots 222, as shown, which are adapted to receive a pin 224 projecting inwardly from the gear 210 in one position of the member 215. The hub 215 is also provided with a peripheral lgroove 226 within which the pin 224 is freely movable; With this construction when the hub 215l is locked in the position shown in Figure 11, the pinion 210 is freely rotatable thereon, but when the hub 215 is moved to the right. the pin 224 engages in one of the longitudinal slots 222 locking the gear against rotation, and in consequence holding the standards 202 in adjusted position. The plate frame 204 is supported by the standards in such a manner that it may be readily adjusted into any desired angular position with respect to the table while maintainingthe center of the screen carried thereby in alignment with the anode or center of the tube. This permits the proper position of the screen to be secured in making X-ray examinations, for example, of a very stout patient. To this end the head 206 carries a yoke 230 which is swivelled upon a stem 232, projecting inwardly over the table from the head, as indicated in Figure 15. This stem 232 is secured in a hub 234, which is journaled upon a pivot pin 236, and held in adjusted position by a clamping screw indicated at Y238. The yoke 230 is locked against swivelling movement to the stem 232 through a clamping member indicated at 240. Through 'the provision of these two adjustments, the

yoke may be swivelled about the axis of the stem 232. 1

From an observation of Figure 16 it will be noted that the hub 234 is provided with stop faces 235 and 237 respectively. which are adapted to engage with a web 239 formed upon the support to retain the lyoke and screen frame carried thereby in either a position parallel to the table or normal thereto. In the parallel position. as shown in the drawings, the screen projects over.

the tableand in the vertical position the screen is displaced out of the way, as for example when in employing a source of X-ray above the patient. The screen and plate frame 204 is pivoted between the opposite arms 242 ofthe yoke vin such .a manner that the ,frame may be readily removed and. turned vthrough anangle of 90 and re-inserted between the arms of the yoke. 'This quickly detachable connection betweenJ the frameand the yoke, and the provision for supporting the frame inv two different positions, is important because it permits the use o f a smaller screen than otherwise.

In the illustrated embodiment of the invention, a luoroscopic screen having dimensions approximately 11 x 15 inches isfemployed, with the long dimension normally extending lengthwise of the table, and the short dimension transversely of the table. This ordinarily suilices for all examinations which it is desired to make. In

certain instances, however, it may be desirable to cover. a space transversely of the table greater than' that embraced in the 'width of the screen, vand in this case the position of the screen may be' changed so that the long of this stud is provided with 'a reduced threaded portion 250 (see Figure 417 which v receives a clamping nut'252.` In addition the end 250 is slotted longitudinally' at 254, and a collar 225 slidesl upon the stem provided with a in 256 engaging within the Thisv colar is normally, forced out,- wardly by a. spring 258, butwhen forced inwardly by the clamping .nut 252 is adapted to seat in Aa recess 260 formed in the bos-ses l262 in the outer ends of the -arms 242. These bosses 262 are alsol, provided with open sided passages 264 which receive the stems 248. With this construction, the

frame is inserted between the` arms of the yoke and the stem 248 positioned within the open sided recesses 264. Thereafter they clamping nuts 252 are turned to force the collars 225 into the recesses 260, thus retaining the studs in position within the* bosses. By tightening the clamping nuts 252 until the bosses 244 are pressed tightly against the arms of the yoke, the frame is held rigidly in position without turning. When it is desired to move the fr ame, this can be readily accomplished by backingv offthe nuts until4 the collars 225 are released lfrom the recesses by the cooperating .spx-ings, thus pernnttmgthe frame to be droppedfout Jfrom the yoke and re-inserted in a new position. The detachable connestionsabove described also permit the screen to be adjusted into different angular positions with respect to the supporting yoke, as willbe obvious to those skilled in the-art. The handling of the frameis conveniently accomplishedby the loperatonthrough the medium of knobs 266, of lead or other material, mounted uponA the upper portion of the frame, as indicated. This frame carries the screenv upon'whieh Athe image is cast, and in addition a protective shield of lead glass above the screen, which permits a view of the image `but protects the eyes of the operator from the X-ray emanations. In addition, the frame is provided beneath the screen with a pocket which slidingly receives 80 .A

a casstetecor plate holder indicated at 270. The location of the'plates immediately beneath the screen and at approximately the same distance from the source of X-ray is important, as it insures that the radioi graphic plates cover the same field `as that shown upon the screen.

The present invention is providedv with\ mechanism :for adjusting the dimensions' of the shutter opening to produce `any desired 'size of image whatever the position 4of 'the screen and plate with respect tothe source of X-ray.' To this end a stationary dial 272 is mounted upon an extension of the head 200 where -it is conveniently visible to the operator, and cooperates 4with the shutter controlling mechanism. In addition the standards 202 are graduated, as shown in` Figure 1, to indicate the distance of the screen frame fromthe source of X-ray.` Upon referring to Figure 12, it will be noticed thatthe dial 272 is provideg` with a table termed Active field which 1s so arranged that knowing the height of the screen frame as indicated by the graduations on the stand- .105 I ards, the width and length of the shutter opening may be determined forl an given dimensions of image. With the wi th and length of the shutter opening known, the controlling mechanism may. he accordinglymanipulated tothe desired'degree. Cooperating with the dial are two indicator hands 274 and 276 which are connected respectively with the -.two sets of shutters controlling the Width and length ofthe opening. These in- .U5

dicator hands are independently securedl -to tubular shafts 278 and 280 which are rotat-l able upon a stationary post 282. The shafts. are connected at their upper ends with knurled operating handles 284 and 286, re- 129 spectively, qand-are -so arranged that the shafts ma be turned together or independently, as esired. To this end, the shaft 280 slides upon the shaft 278 until a datent pin 290 carried upn the handle 284l engages 125 within a recess 292 formed inthe handle 286 Vlocking both handles together. In this position both shafts and indicating hands are turned together to operate the shutters'. jointly. When the handles are released,

I Each indicator hand is connected with a set lll handles tends to move them into the relative position shown in Figure 13, in which position either handle may be moved independently of the other to give the proper independent adjustment of the shutters, as indicated by the position of the hands with respect to the graduations upon the dial.

of shutters to open or close each set, according to the direction in which the hand is moved. One pair of shutters is indicated at 300 and 302, and a second pair of shutters, moving at right angles thereto, is indicated at 304 and 306. The shutters 300 and 302 are supported above the shutters 304 and 306, and as indicated in Figure 9, the shutter 300 is supported at one end upon a bar 308, and the shutter 302 is supported at the opposite end upon aber 310.v The two bars 308 and 31() are pivot-ally connectedI at opposite ends to centrally fulcrumed levers 312 and 314 in such a manner that `as the levers are rocked about their axes, the bars 308 and 310 are moved in alengthwise direction, always maintaining their parallel relationto increase or decrease the space between the shuttersl carried thereby, as will be evi-` dent. In order to secure the requisite movement of the frame, the bar 310 as shown is connected to the corresponding indicator hand through a connectng rod 316, and a pivot lever 318. The under shutters 304 and 306 are moved toward and from one another in a similar manner, but at right angles to the direction of movement of the shutters 300 and 30 2. For this purpose the under shutters, as shown, are; mounted upon parallel bars 320 'and 322, pivotally connected at opposite ends to levers'324 and 326. The frame carrying these shutters is moved the desired amount by a connecting rod 328 connected at one end with the corresponding indicator hand and at the other end to the pivoted lever 330 which is connected in turn to the lever 326 through a pin 327 and cam slot 329 formed in an extension 331. It will be obvious to those skilled in the art that with this construction the shutters may be simultaneously or independently adjusted to provide a rectangular opening of the requisite size to produce an image of the desired` dimensions upon the radiographic plate or screen.

As the weight of the table and mechanism supported thereby is considerable, it is quite essential that .some means be providedl for accurately counter-balancing the table and connected mechanism in any longitudinal position of the tube carriage. In order to effectthis result, the stationary transformer 371 is designed to accurately kcounter-balance the table itself in any inclined position. It will be observed from an inspection of Figure 1 that with this end in provided with a hollow tube 340 within which slides al counter-weight 342 which may have anti-'friction bearings as shown clearly in Fig. 19. The opposite ends ot the counter-weight am connected respectively with opposite ends vof the tube carriage through flexible cables 344 and 346, which pass about pulle s 348 and 350 journalerl respectively in t e tube 340 and the end casings 99 and 101, as shown clearly in Fig- -ure 19. In order to maintain the cables taut and avoid any shock or jar in moving ythe carriage, one of the cables 1s connected to the carriage through a spring connection' as indicated generally at 352 in Figure 18. This connection comprises a casing 349 threaded upon a connector stud 351 and receiving a spring 353 which forms a yielding connection between the cable and `casing 349. When the carriage is in the position shown in'Figure 2 of thedrawin s atrone end` of the table, the counter-weig vt 342 is located within the tube at the opposite end and as the carriage is moved downwardly in the drawings the counter-weight is moved in the opposite direction a like distance. With this construction in actual practice the table ma be rocked when the motor is disconnecte with a very slight pressure.

As will be observed from an inspection of Figures 1 and 2 of the drawings, the X-ray tube is connected with the transformer through connections designed to automatically take up or pay out as thc tube car- 'riage is moved relative to the transformer. To this end the filament end of the tube is connected to the transformer by leads 360 and 362. These leads at the tube end pass over spring sheaves 364 and 366, as shown in Figure 2, which constantly tend to rotate in a direction to maintain the leads taut. Thus, as the tube carriage is moved toward the transformer, the sheave members 364 and 366 rotate to wind up the leads, and as thc tube carriage is moved in the opposite direction, the members are rotated against thc tension of the spring to pav' out the leads. The opposite end of the tube is also connected with the transformer through a lead indicated at 367', which passes over a similar sheave 368 and from this point to the tube through a flexible connection 370. The

`cathode memberv is connected to the transformer 371 through a stationary conductor 372, passing into the bottom of the trans- `former box. It will be observed that with this construction the high tension leads connecting thev transformer with the tube are located beneath the table in a position where there is no liability of fthe operator coming in contact with them. To .provide an additional safeguard, the tube is irovidedwith two guard rails 374 and 37 6 which are connected at opposite ends to the operating segment 17 and to an outwardlv projecting arm ,378, as shown in `Figure 1. The tube .is

housed on opposite sides by plates 379-of bakcliteorsimilar insulatina material.

Means are provided for conveniently controlling the operation of the tube, andv to this end a resistance control for .the filament is located in a position Conveniently accessioleto the operator. Upon referring toFigures 1, 2 and 31, it will be seen that a resistance 380 is mounted yupon a plate 382 supported by the transformer box, this resistance being connected into thefilament circuit. The control of the resistance is se cured through a movable contact member 4384,`v'vhich is mounted upon a rotatable lead screw 386 journaled in brackets 388; and 389. The lead screw projects diagonally upward into a position where .it may be manipulated by an operator standing at one side of the table.y The upper end of the screw is provided with an operating handle 390 by which it may be rotated to .traverse the Contact 384 lengthwise of the resistance. It will be observed, upon referring to Figure 31,'that the lead screw is provided with a thread of steep. pitch so that a -slight y rotation of the handlewill cause a comparatively large movement of the contact. In addition to this convenient method otl control, the table is provided with meansfor instantlyy renderingthe tube inoperative, if so desired. Tozhisend an operating cord indicated at 39 extends along the front of vthetable, as shown in Figure 1, and is connected with a pullv switch 394 of any usual type, which, when operated by a pull upon the cord, disconnects thetube circuit. It

will be observed that this operating cord extends throughout substantially the ent-ire' length of the tableso that it may be vconveniently manipulated in any position of the operator. The transformer carries a milliammeter `373 which indicatesto the 'op-v erator the current consumed.

' vThe table, as thus far described, is adapted for X-ray examinations or the taking of radiographs with the tube located beneath the table. In addition, it is desirable to provide means for taking stereoscopic radiographs, and this is preferably accomplished -in the present invention by a second tube supported above the table and plates supported beneath the table adapted to record 'the desired image. The plate holder carrying' the plates for this purpose conveniently .move the plate'holder into one cause it to operate against the s irings. A l. plate carrymg frame 400 is accor ingly supported for movement between the two\ang1e irons 137 upon which the bed of the table is mounted. This plate carrying frame and the construction for supporting and shifting it are shown more particularly in Figures 17 to 25, inclusive, of the drawings. As will be observed from an inspect-ion of Figures 21 and 22, a rectangular wooden frame, 402 isde'signed to receive two plates` end to end, a distance piece 404 serving to separate" the two `plate holders. The upper face of the plate carrier is provided with metal strips 406 which enclose an opening` of the desired size and provide an inwardly projecting ledge for retaining the `plate holders rn position. The opposite side of the plate carrier 400 'islprovlded with quarter round mouldings 40S-located within the opening and adapted to hold the plate holders in kpcsition against the ledge in conjunction with a spring latch 410. vUpon referring to Figure 22, it will be obvious to those skilled in the art the manner in which the plate hold'- ers may be thrust into the opening and held' in place.` The plate carrier 400 is provided upon its opposite sidesl with tongues 412 4having recesses 414 which receive a horizontal flange-416 formed ,upon supporting angles 4 18 secured tothe main supporting irons 137, as'fshown in Figures 25 and 26. This `construction provides parallel tracks along which then plate 'carriermay slide immediately beneath the bed of the table.4 The plate carrier is normally retained in one position by tension springs 419 and 420, which connect a bar 422 secured to one end of the frame with a transverse bar 424 rigidly connected to the end casting 99. In addition mechanism is provided for locking the plate carrier in one of two positions, and for conveniently releasing the carrier" to permit it to be shifted by the. springs to a second position. .To this end the plate'carrier lis provided with a transversely projecting handle 420 carrying a head 428 which slides upon a stationary tube 430, as shown clearly 1n Figures 1 and 24. This tube is provided with two openings 432 which correspond respectively to the two positions of the plate carriers. These recesses lare adapted to be engaged by 'the inner -end of a' locking plunger 434 slidingly supported within the ead, and normally moved into locking position by a spring .436 received within a recess in the head and enclosed between the plunger and a cap screw 438, as shown in 'Figure 26. When in locking position, the

inner end of the plunger 434 projects in the tube sufliciently to be engaged by the wedge shaped ends of the releasing members 440 and 442 connected to a releasing 'rod 444, which slides within the tube. 'lhe releasing rod extends substantially throughout the length of the table, being slidingly supported at opposite ends by brackets 446. 'lhe opposite ends of the rod are provided with handles 448`and thel rod is normally retained in an inoperative position, as shown in Figure 24, by a spring 450. The opera.- tion of the above described construction is substantially as follows.

After the plate holders have been inserted within the plate carrier, the latter-is moved by the handle 426 into a position in which the springs 420 are tensed and locked in this-"position for engagement .of the-.detentof the corresponding opening in the tube. After the first radiograph has been taken in this position, the releasing rod is, moved lengthwise to elevatethe plunger' suiliciently in the opening to cause the wedge-shaped end of the plunger to engage with the walls of the opening and thereafter the strength of the spring 420 is sufficient to complete the unlocking movement of the plunger, and immediately shift the plate carrier as a whole into the second position. The plate carrier is then locked automatically in this position by the engagement of the plunger with the second opening in the tube. When the table islocked in a vertical or substantially vertical position, however, the first picture is taken with the plate holder in the second position, as above described. Thereafter the locking means are released to permit the weight of the plate holder to move it into the iirst position by gravity against the action of the springs. It will be obvious to those' skilled in the art that the locking' means are so designed that they will firmly hold the plate holder in either one of two positions, irrespective of the inclination of the table. By operating the plate holder in this manner it is not necessary to employ as powerful a shiftingmechanism, andthe resultant sliock and jar are largely reduced.

In order to prevent the shock which would normally be incident to the rapid shifting of the plate carrier, means are provided for checking the movement of the carrier at' the completion of the shifting movement. To this end a hollow cylinder 452 is secured to the front of, the table adjacent the releasing rod, as shown in Figure 24, and receives a piston 454, connected with a piston rod 456 slidingly received in a'bracket 458. The piston rod is provided with spaced collars 460 and 462 which are adapted to be engaged by the head 428 when moving the plate carrier longitudinally. The cylinder 452 is closed at the opposite ends, but is provided with a relief opening controlled by a suitable form of spring operated valve 464. vAs shown in Figure 27, the valve 464 comprises a needle valve 466 controlling a small opening- 468 which enters the cylinder adjacent the4 closed end. This construction forms in eii'ect a dash pot which serves to check themovement of the plate -carrier in either direction whenr near the end of its stroke. When the plate carrier is moved in one direction through the handle 426, the4 engagement of the handle with one ot' the coll'ars moves the piston 454 to the right, as shownin Figure 23, and thereafter the plate carrier is released and the returning movement due to the springs causes the head to engage with the collar 462 near the end of the stroke and actuate the dash pot to check the movement and bring the plate carrier gently into position.

The overhead tube employed in connection with the stereoscopic plate holder is mounted above the table upon a vertical standard 470. This tube, which may be of any usual form (not shown) is preferably adjustable with' relation to the standard into any one of a number of angular or vertical positions. The tube carrying standard 470 is supported by brackets 472 and 474 which travel upon 190 upper and lower guide rails 476 and 478 connected at their opposite ends to supports 480 and 481, all as shown in Figures l and 2. The brackets 472 and 474 are each provided with three anti-friction rolls 486165 which engage with opposite sides of the tubular guide rails 476 and 478 to facilitate the movement of the brackets thereon. 'lhis construction permits the overhead tube to be conveniently moved into any position longitudinally of the table. As will be observed from an inspection of Figure 2, the supports and tubular guide rolls are connected with the side support 13 through connections 490.

Having thus described the invention, what for counter-balancing the source of X-ray in any position of the latter with respect to the table.

2. An X-ray apparatus comprising supporting members, a table connected thereto near one end for rocking movements, an X- ray tube carriedby the table, and a transformer mounted .upon the table to counterbalance the table in its various positions.

3. An X-ray apparatus comprising a ,screen frame, threaded studs projecting 4. An X-ray apparatus comprising a sup` porting yoke having open sided passages formed in the ends of the arms, a ,screen frame, threaded studs projecting from opposite sides of the screen frame, and means for locking 'the studs in the open sided passages formed in the arms of the yoke, adapted to permit the frame to be adjusted angularly with respect to the yoke.

5. An X-ray apparatus comprising a pivoted table, a carrier adapted to contain two plate holders, means for slidingly support ing the carrier, mechanism for lockingr the carrier in an operativev position, spring mechanism for normally moving the plate carrier to a second operative position upon release ofthe said locking mechanism, means for locking the carrier in the second position,

the plate carrier having sufficient weight 'to allow of motion from the second position to the first mentioned position against the action of the spring mechanism when the table is upright. l

6. An X-ray apparatus comprising a, table, a carriage movable longitudinally of the table, a yoke mounted on the carriage, a rectangular screen adapted to be supported by the yoke and having a boss on each side of such length that the screen may be supported in the yoke either longitudinally or transversely of the table, and means for connectingtwo opposite bosses in the arms of the yoke. y'

7. In combination, a support, a table rotatably mounted on said support and adapted to be tilted through a vertical are, an X- ray tube mounted on said table and a transformer mounted on said table below the axis of rotation' thereof and connected to said tube.

8. In combination, a support, a table rotatably mounted on said support, a carriage movable longitudinally of said table,'an X- ray tube mounted on said carriage, a transformerv mounted on the rear side of the table at the rlower end thereof and conductors connectingg the transformer with the tube.

CHARLES E. CAMPBELL. 

